A2A Integration
Overview
A2A (Agent2Agent) is an open protocol by Google for agent-to-agent communication. It defines standard types for tasks, messages, artifacts, and streaming events — so agents built with different frameworks can interoperate.
mq9 acts as the transport layer for A2A. Instead of running an HTTP server, each agent registers its AgentCard in the mq9 registry and receives tasks via its mailbox. Any A2A-compliant client can discover and send tasks to any mq9 agent — regardless of what language or framework built them.
Language independence
Because mq9 is the shared transport, agents written in different languages work together out of the box:
- A Python agent (
Mq9A2AAgent) can receive tasks from a Go client - A Java agent can call a Python agent using standard A2A
SendMessageRequest - Any language that speaks A2A over mq9 can communicate with any other
The broker holds the mailbox and registry — it doesn't care about the language on either side.
How it works
| Step | What happens |
|---|---|
| ① Agent A startup | Agent A calls MAILBOX.CREATE, then AGENT.REGISTER with its AgentCard |
| ② Agent B discover | Agent B calls AGENT.DISCOVER with a natural-language query; broker returns matching agents |
| ③ Send task | Agent B sends SendMessageRequest to Agent A's mailbox, with a callback mailbox in the mq9-reply-to header |
| ④ Stream events | Agent A processes the task and sends A2A events (Task, working, artifact, completed) back to the callback mailbox one by one; the last event carries mq9-a2a-last: true |
mq9 replaces the HTTP+SSE transport that A2A typically uses. Each streaming event is one mq9 message on the callback mailbox.
SDKs
| Language | Package | Status |
|---|---|---|
| Python | mq9 (built-in) | Available |
| Go | coming soon | Planned |
| Java | coming soon | Planned |
| JavaScript | coming soon | Planned |
| Rust | coming soon | Planned |
| C# | coming soon | Planned |